The present invention relates generally to data communications, and particularly to conversion between different data communication channel media.
A data communication channel permits data communication between devices such as computers, switches, and the like. Data communication channels are available in different media to suit different applications. For example, copper media is often used for indoor channels due to low cost and ease of installation, while optical fiber is often used outdoors due to its immunity to electromagnetic disturbances such as lightning strikes, and due to its superior signal attenuation characteristics which support longer distances.
When it is necessary to connect channels of different media, a media converter is required. FIG. 1 shows a conventional installation. Two devices 102A and 102B are connected to two switches 104A and 104B, respectively. Switches 104 are connected by a channel 106 that includes a copper channel 110A, a fiber optic channel 110B, and a second copper channel 110C. Fiber optic channel 110B is connected to copper channels 110A and 110C by media converters 108A and 108B, respectively.
A common problem with the installation of FIG. 1 occurs when one of channels 110 goes down. For example, assume channel 110A goes down. Both switch 104A and media converter 108A detect this condition and therefore provide a “link down” indication. However, this information does not propagate across links 110B and 110C to converter 108B and switch 104B, which continue to provide a “link up” indication because the status of channel 110C is “link up.” This “link down” propagation is important so that switch 104B can take appropriate action due to the link 106 being down. One form of appropriate action is to inform the network administrator of the problem or to reconfigure the network using a backup link to switch 104A. Non of this can be done without the propagation of the “link down” status.
One solution is to add sensors to channels 110A and 110C to detect “link down” status, and to propagate that status across channel 110B to the converter 108 and switch at the other end. One disadvantage of this approach is that such an arrangement renders channels 110A and 110B to be non-compliant with network standards such as those published be the Institute of Electrical and Electronics Engineers (IEEE).
Another disadvantage of this approach is the cumbersome process required to reestablish “link up” status. One approach is to provide a manual control on each switch 104 that forces “link up” when operated. One disadvantage of this approach is that human intervention is required. Either one person must travel to both switches 104, or two persons must coordinate the operation of the controls by some communication means other than channel 106.